Where does the waste material in the body come from and why does the body need to get rid of these waste materials?

In your body, the excretory system helps to keep salts and urea from building up to dangerous levels and becoming toxic. The kidneys are two bean-shaped organs that remove thesetoxins from your blood and produce urine to carry them from the body. Waste products must be removed from the body. If they are not, they will increase in concentration and may interfere with chemical reactions or damage cells. Waste products that must be removed include carbon dioxide and urea.

"The cells of the body produce waste materials. The body needs to get rid of these waste materials because they can make us sick. Getting rid of this waste keeps us healthy."

This is not my answer, but rather the sample answer from the school program. I do not take the credit, I'm just here to help!               - Bella